<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>7B2布局</title>
</head>

<body>
    <div class="site">
        <div class="header">顶部菜单</div>
        <div class="content">中间内容</div>
        <footer class="footer">底部菜单</footer>
    </div>
    <style>
        .site {
            background-repeat: no-repeat;
            background-attachment: fixed;
            background-position: center top;
            background-color: #eff1f3;
            display: flex;
            min-height: 100vh;
            flex-flow: column;
        }

        .header {
            height: 58px;
            margin-bottom: 16px;
            background-color: aliceblue;
        }

        .content {
            padding-bottom: 0;
            flex: 1;
            background-color: bisque;
        }

        .footer {
            color: #333333;
            font-size: 13px;
            display: block;
            background-color: violet;
        }

        body {
            padding: 0;
            margin: 0;
        }
    </style>
</body>

</html>